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INFLUENCE OF CENTRALIZED AND DISTRIBUTED THERMAL ENERGY STORAGE ON DISTRICT HEATING NETWORK DESIGN

Joseph JebamalaiInnovation Engineer, Comsof, Belgium and PhD Researcher, Ghent University, Belgium

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OVERVIEW – STORAGE CONFIGURATIONS

• Centralized storage• Substation level storage• Building level storage

Centralized vs Distributed thermal energy storage

Centralized storage Distributed storage

• What is the impact on total network cost, consisting of:o Heat source costo Storage costo Network pipe systems costCan we find an optimum storage size?

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CASE STUDY – METHODComsof heat and excel based storage calculations

Use of Comsof Heat for o Automated network routing o Pipe size dimensioningo Deployment cost calculation

(excl. storage costs)

• Use of Excel foro Storage tank

dimensioningo Calculation of storage

costs

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CASE STUDY - INPUTS

BUILDING:• Street level gas consumption data

• Building types are categorized as:o Residential o Commercial o Industrial

• Synthetic load profiles

HEAT SOURCE:• Heat source: IMOG, waste incineration plant

o 2 km from the networko Available heat 130 GWh / yearo Source peak capacity 15 MW (Continuous operation)

Selected 2328 buildings and heat source – Kortrijk, Belgium

Case study area

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CASE STUDY - NETWORK

• Building demand Load profiles, annual gas consumption data

• Network demand Aggregation of building heat demand

• Network annual heat demand – 95 GWh/year

• Network peak load – 34 MW (without storage)

Network demand and peak load

Daily profile of different building types

Hourly network heat demand

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CASE STUDY – STORAGE

2 – LAYER NETWORK:• Transport and distribution network

STORAGE DESIGN:• Production profile Constant throughout the year

• Consumption profile Winter peak

• Surplus / Deficit over certain timeo Charge storage when there is surpluso Discharge storage when there is deficit

• Maximum storage size Energy produced ~= Energy consumed

2 - layer network and storage design

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CASE STUDY – CENTRALIZED STORAGE

• Source power reduction

• No change in pipe sizes

• Maximum storage size – 450,000 m3

• Source power can be reduced up to 11 MW

• Minimum total network cost occurs at 1% storage o Source peak power around 22 MWo Storage size around 4500 m3

o 3.5% cost reduction

Source peak power vs Storage size – Seasonal storage

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CASE STUDY – SUBSTATION LEVEL STORAGE

• Source power reduction

• Reduction in transport network pipe sizes

• Constant distribution network cost

• Increasing storage size (for every substation size)o Reduction in transport network costo Minimum total network cost at 1% storage (4500 m3)

• Total minimum network costo 2 MW substation and 1% storage (4500 m3)o 7% cost reduction

Transport and total network cost – Seasonal storage

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CASE STUDY – BUILDING LEVEL STORAGE

• Source power reduction

• Reduction in transport network pipe sizes

• Reduction in distribution network pipe sizes

• Maximum daily storage size - 1086 m3

o Source power can be reduced up to 22.5 MW o Total network cost - 10% cost reduction!

• Seasonal storage o Minimum total network cost at 22600 m3

‒ 12% cost reduction!

Source power and total network cost – Daily and seasonal storage

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CASE STUDY – BUILDING LEVEL STORAGE

• Average storage tank size per building:

Network cost - Daily storage at different building types

Building level storage (Daily storage)

Type Average storage size (Liters)

Total storage size (m3)

All buildings 461 1086Residential 400 700Commercial 286 156

Industrial 3992 232

10% 6% 1% 2%Cost reduction

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CONCLUSION

• Successful use of software package Comsof Heat in combination with manual excel based storage calculations

• The more distributed storage, the lower the network cost (due to pipe size reductions):

FUTURE WORK:• Investigate the effect of different profile types

• Integration of the concepts in Comsof Heat

Overview and future work

Storage location Storage type Storage size

(m3)No. of storage

tanksCost reduction

(%)Centralized Seasonal 4500 1 3.5

Substation level Seasonal 4500 18 7

Building level Daily 1086 2328 10

Building level Seasonal 22600 2328 12

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